Vertical flow wrapper with improved production time

Abstract

The invention relates to improvements of a cross-sealing and cutting means for a vertical flow-wrapper, which produces packages. The invention also relates to a set of a cross-sealing and cutting members and a method to improve the tool-life of a first cross-sealing and cutting-member.

Description

[0001] Vertical flow wrapper with improved production time

[0002] The invention relates to improvements of a cross-sealing and cutting means for a vertical flow-wrapper, which produces packages. The invention also relates to a set of a crosssealing and cutting members and a method to improve the tool-life of a first cross-sealing- and cutting-member.

[0003] A common method of making packages out of a film web is the use of a vertical flowwrapper. Such a packaging machine receives a continuous flat sheet, for example a film of plastic material, e.g. a thermoplastic material, which is transported continuously or intermittently and passed downwardly over a form shoulder and is then shaped into a tubular form, i.e. into a film tube, by being wrapped around a vertical form-fill tube of the packaging machine. After being wrapped around the vertical form-fill tube, the film web is longitudinally closed by means of a longitudinally extending seal which is applied to the film especially by heat sealing the lateral / longitudinal margins of the film web or by heat sealing in the vicinity of these margins thereby joining them. This is carried out by so called longitudinal-sealing means. The film tube has conventionally a rectangular, elliptical or a circular cross-sectional area. The film tube is closed by cross-sealing means, preferably in a direction perpendicular to the direction of flow, i.e. transversely. Thereby, individual packages are defined out of the continuous film tube. A product, such as a foodstuff, is introduced by dropping the product through a form-fill tube and into the film tube surrounding the form-fill-tube. During filling, the film tube is transversely open at its upper end, i.e. not cross-sealed. Thereafter and / or simultaneously, the film tube together with the product is moved downwardly and then a top cross-seal is formed above the product and thereby a hermetically closed package produced. As a last step or simultaneously to the application of the top seal, the package is separated from the film tube by cutting means by cutting the film in a cutting plane.

[0004] The cross-sealing means conventionally comprise a first and a second cross-sealing- and cutting member, which are provided on opposite sides of the film tube and which each reciprocate from a remote- to a sealing / cutting position and vice versa. The first crosssealing- and cutting member is for example a sonotrode and the second cross-sealing- and cutting member for example an anvil. Together they form an ultrasonic sealing means. Particularly the sonotrode is an expensive part and there is a constant desire to increase its tool-life. The purpose of the invention is therefore to provide a Cross-sealing and cutting means for a flow-wrapper with an improved tool-life and a method to improve the tool-life of a first cross- sealing- and cutting-means.

[0005] The purpose is attained by providing a cross-sealing and cutting means for a flow-wrapper comprising first- and second cross-sealing- and cutting members, which cooperate during sealing to apply a pressure to a film to be sealed and during cutting of the sealed film tube, wherein the first cross-sealing- and cutting member comprises an indentation provided in a plane and the second cross-sealing- and cutting member comprises: a cutter, which, during cutting enters the indentation and

[0006] - two convexities, one convexity having a first distance from the plane and the other convexity having a second distance from the plane, wherein the distances are not equal.

[0007] The disclosure regarding this embodiment of the present invention also applies to the other embodiments and vice versa. Subject matters disclosed regarding one subject matter can be included into another embodiment and vice versa.

[0008] The present invention relates to the cross-sealing and cutting means of a vertical flowwrapper. The flow-wrapper has a frame and / or a housing, which receives a continuous flat sheet, e.g. a film of plastic material, e.g. a thermoplastic material, which is transported continuously or intermittently and passed downwardly over a form shoulder and is then shaped into a tubular form, i.e. into a film tube, by being wrapped around a vertical form-fill tube of the packaging machine. After being wrapped around the vertical form-fill tube, the film web is longitudinally closed by means of a longitudinally extending seal which is applied to the film especially by heat sealing the lateral / longitudinal margins of the film web or by heat sealing in the vicinity of these margins thereby joining them. This is carried out by so called longitudinal-sealing means. The film tube has conventionally a rectangular, elliptical or a circular cross-sectional area. Conventionally, the film tube is closed by cross-sealing means, preferably in a direction perpendicular to the direction of flow, i.e. transversely. Thereby, individual packages are defined out of the continuous film tube. A product, such as a foodstuff, is introduced into the film tube by dropping the product through a form-fill tube and into the film tube surrounding the form-fill tube and onto a lower-, first cross seal. During filling the film tube is transversely open at its upper, top end, i.e. not cross-sealed. Thereafter and / or simultaneously, the film tube together with its product is moved downwardly and then a top cross-seal is formed above the product and thereby the hermetically closed package is produced. As a last step or simultaneously to the application of the top seal, the package is separated from the film tube by cutting means.

[0009] The cross-sealing and cutting means according to the present invention comprise first- and second cross-sealing- and cutting members, which cooperate during sealing to apply a pressure to a film to be sealed and during cutting of the sealed film tube. The comprise firstand second cross-sealing- and cutting members are provided on opposite sides of the film tube and each reciprocate from a remote- to a sealing / cutting position and vice versa. The first cross-sealing- and cutting member is for example a sonotrode and the second cross- sealing- and cutting member for example an anvil. Together they form an ultrasonic sealing means. The person skilled in art however understands that one or both of the tools can be heated to facilitate the sealing of the film tube.

[0010] According to invention, the first cross-sealing- and cutting member comprises an indentation, in a preferably plane surface, for example a slot, provided in a plane, preferably a cutting plane along which two adjacent packages are separated. The indentation preferably extends preferably over the entire width of the first cross-sealing- and cutting member and / or in a direction up- and / or downwards from the cutting plane; i.e. parallel to the transport direction of the film tube.

[0011] The second cross-sealing- and cutting member comprises a cutter, which, during cutting enters the indentation of the first cross-sealing- and cutting member and thereby cuts the film-tube.

[0012] The second cross-sealing- and cutting member further comprises two convexities, which during sealing are pressed against the first cross-sealing- and cutting member with the film tube being in between. Due to the convexities, well defined seals are provided. One convexity, preferably the first convexity, provides the bottom seal of a bag, while the other convexity provides the top seal of an adjacent bag. The two seals are provided simultaneously. The convexities can be provided in one piece with the first cross-sealing- and cutting member or can be provided separately and is then attached to the cross-sealing- and cutting member.

[0013] According to the present invention, one convexity has a first distance from the plane in which the cutter is provided and the other convexity having a second distance from the plane in which the cutter is provided, wherein the distances are not equal. One distance is larger than the other. Preferably, the deviation between the distances is 2 - 10, preferably 3 - 8 mm. Due to this difference in distance, one of the cross-sealing- and cutting member can be turned after a number of production cycles so that the location at which the convexities are pressed against the first cross-sealing- and cutting member is changed, which can increase the tool life of the first cross-sealing- and cutting member by 100%.

[0014] The problem is also attained with a set of a cross-sealing and cutting members for a flowwrapper comprising a first- and two second cross-sealing- and cutting-members which cooperate during sealing to apply a pressure to a film to be sealed and during cutting of the sealed film, wherein the first cross-sealing- and cutting member comprises an indentation provided in a plane and the second cross-sealing- and cutting member comprises: a cutter, which, during cutting enters the indentation and

[0015] - two convexities, one convexity having a first distance from the plane and the other convexity having a second distance from the plane, wherein the first and second distance of the indentations of one second cross-sealing- and cutting member is different from the first and second distance of the indentations of the other second cross-sealing- and cutting member.

[0016] The disclosure regarding this embodiment of the present invention also applies to the other embodiments and vice versa. Subject matters disclosed regarding one subject matter can be included into another embodiment and vice versa.

[0017] According to this embodiment of the present invention, a set of cross-sealing and cutting members is provided that comprises one single first cross-sealing and cutting member and two second cross-sealing and cutting members. The two second cross-sealing and cutting members differ in the distance between two indentations.

[0018] The operation of the flow-wrapper is started with the first cross-sealing and cutting member and one of the two second cross-sealing and cutting member. After a number of production cycles, for example four million sealing cycles, the second cross-sealing and cutting member is exchanged by the other second cross-sealing and cutting member of the set.

[0019] Due to this change, the location at which the convexities are pressed against the first crosssealing- and cutting member is changed, which can increase the tool life of the first crosssealing- and cutting member by 100%. The problem is also attained by vertical flow-wrapper having the inventive cross-sealing and cutting tool and / or one first- and one of the two second cross-sealing- and cutting-members of the inventive set.

[0020] The disclosure regarding this embodiment of the present invention also applies to the other embodiments and vice versa. Subject matters disclosed regarding one subject matter can be included into another embodiment and vice versa.

[0021] The problem is also solved with a method to improve the tool-life of a first cross-sealing- and cutting member by changing the location at the first cross-sealing- and cutting member against which the convexities of the second cross-sealing- and cutting member is pressed after a number of production cycles.

[0022] The disclosure regarding this embodiment of the present invention also applies to the inventive vertical flow wrapper and vice versa. Subject matters disclosed regarding the method can be included into the inventive vertical flow wrapper and vice versa.

[0023] According to this embodiment of the present invention, the location of the first cross-sealing- and cutting member against which the convexities of the second cross-sealing- and cutting member are pressed is changed after some production cycles. Due this change in location, the tool-life of the first cross-sealing- and cutting member is increased. The number of production cycles can be preset, for example four million or the ware of the surface of the first cross-sealing- and cutting member can be determined and based on this determination the change in location is carried out.

[0024] Preferably, the first or the second cross-sealing- and cutting member is turned by 180° after a number of production cycles around a plane or an axis in the plane. In this embodiment of the present invention, the distance of the indentations of the second cross-sealing- and cutting member to the plane is different. More preferably, the one cross-sealing- and cutting member is turned around an axis perpendicular to a transportation direction of the film.

[0025] According to an alternative embodiment, one second cross-sealing- and cutting member is replaced by a different second a first cross-sealing- and cutting member after a number of production cycles. This embodiment requires that the distance of the convexities at the replacement member differs from the distance of the convexities at the member being replaced. In yet another preferred embodiment, the vertical position of the first- and second cross- sealing- and cutting member is change relative to each other after a number of cycles. Preferably one or both members can be provided at different vertical positions at the flowwrapper. Due to the change of the vertical position of the two cross-sealing- and cutting members relative to each other, the locations at the first cross-sealing- and cutting member against which the convexities of the second cross-sealing- and cutting member is pressed, are different.

[0026] Preferably, a control system provides a signal when the locations against which the convexities are pressed, have to be changed. This signal can alert a worker to make the needed change or the signal is fed to a device which automatically makes the needed change.

[0027] The inventions are now explained referring to the figures of the attached drawings, by way of non-limiting examples. The explanations apply to all embodiments of the present invention likewise.

[0028] Figure 1 shows schematically the vertical flow-wrapper according to the invention.

[0029] Figures 2 and 3 depict an embodiment of a cross-sealing- and cutting means.

[0030] Figures 4a - 4c show the inventive set and the inventive method

[0031] Figures 5a and b shows the inventive cross-sealing- and cutting means and the inventive method

[0032] Figure 6 shows an embodiment of the inventive method

[0033] In Figure 1 , the vertical flow-wrapper 1 according to the invention is schematically shown. A vertical flow wrapper is a packaging machine, which forms a plane film web into a film tube, which is transported along a form-fill tube 4. Two ends of this film tube are sealed together by a longitudinal sealing means 5. Subsequently, the packaging item is filled into the film tube and a cross-seal is applied to the film tube to close the package. Simultaneously or after applying the cross-seal, the finalized packages are cut off the film tube. The vertical flow wrapper comprises a frame / housing 8, at which a form shoulder 3, a form-fill tube 4 and longitudinal sealing means 5 and cross-sealing means 6 are provided. The vertical flow- wrapper may comprise gusset- forming means to form the bottom and / or the top of each package.

[0034] A web of a film 4, especially a weldable plastic film 4, is supplied from a reel 9, which supplies the plane film continuously or intermittently to a form shoulder 3, which shapes the film web into a rather tubular form around a form-fill tube 2. In the context of the present invention, a “tubular form” of the packages or of the film means any cross-sectional form including a circular form or another form, and especially a rectangular or generally a polygonal form. Longitudinal sealing means 5, which are provided downstream from the form shoulder, seal the edges to the film tube together. After sealing, the bottom of the package 7 can be formed by a special bottom forming means, for example gusset-forming means. Finally, cross seals, extending preferably perpendicularly to the direction of flow of the film, are applied, especially by means of cross-sealing means 6. These cross sealing means 6 apply to the package 7 not only an upper / second cross-seal closing the top of the package 7, but these cross-sealing means 6 advantageously also provide, preferably simultaneously a lower / first cross-seal defining the bottom of the subsequent, upstream package 7. The packages 7 produced are separated from one another by a cutting means, which are preferably incorporated into the cross-sealing means 6. Between the application of the bottom- and top-cross-seal of each package, the package is filled with the product, preferably an edible product.

[0035] Figures 2 and 3 show an embodiment of a cross-sealing and cutting means 6. This crosssealing and cutting means 6 comprises a first and second cross-sealing- and cutting member 6.1 ., 6.2 provided on two opposite sides of the film tube to be sealed. The first cross-sealing- and cutting member 6.1 can be for example a sonotrode of an ultrasonic sealing device. The second cross-sealing- and cutting member 6.2 is for example an anvil. The surface of the first cross-sealing- and cutting member that faces the film tube is preferably a flat plane. The first cross-sealing- and cutting member 6.1 comprises ab indentation 15 that extends around a plane 12. The second cross-sealing- and cutting member has a cutter 11 , that is provided in the plane 12. The cutter 11 is preferably movable relative to the second cross-sealing- and cutting member 6.2. Two convexities 13, 14 above and below the plane 12, preferably the cutting plane, are depicted, wherein the first convexity is provided at a distance D1 form the plane 12 and the second convexity at a distance D2 from the plane 12. The first- and second cross-sealing- and cutting member 6.1 , 6.2 are reciprocated between a sealing position (not depicted), in which the convexities 13, 14 are pressed against the surface of the first crosssealing- and cutting member 6.1 and a remote position (depicted), for example by a horizontal movement. The convexity 13 in corporation with the first cross-sealing- and cutting member 6.1 applies the bottom cross-seal of each bag being produced. The convexity 14 in corporation with the first cross-sealing- and cutting member 6.1 applies the top cross-seal of each bag being produced. After or while the cross-seals are being applied, the cutter is moved in the direction of the film tube, preferably at least partially independent from the movement of the second cross-sealing- and cutting member 6.2 and partially immerses into the indentation 15 and thereby separates the finalized bag from the film tube.

[0036] Figure 3 depicts that the convexities 13, 14 preferably extend over the entire length of the second cross-sealing- and cutting member 6.2.

[0037] The above said also applies to all inventive embodiments of the present invention.

[0038] In the embodiment shown in Figures 2 and 3, the distances D1 and D2 of the convexities 13, 14 from the plane / axis 12 are the same or essentially the same, which is state in the art.

[0039] Figures 4a - 4c depict the inventive set and the inventive method. Reference is made to the elaborations according to Figures 2 and 3. It can be seen one single cross-sealing- and cutting member 6.1 and two different second cross-sealing- and cutting member 6.2 are provided as a set, wherein simultaneously only the first cross-sealing- and cutting member 6.1 and one single second cross-sealing- and cutting member 6.2 are attached to the vertical flow wrapper. The second cross-sealing- and cutting member 6.2 depicted in Figure 4a and Figure 4b differ by the distance D1 , D2 of the convexities from each other and / or by different distances from of the convexities from the plane 12.

[0040] Figure 4c illustrates the difference in the distances D1 , D2. The convexities 13, 14 depicted in dashed lines are provided at one cross-sealing- and cutting member 6.2 and the convexities 13, 14 depicted in continuous lines are provided at a different cross-sealing- and cutting member 6.2. It can be clearly seen that the locations 16 at which the convexities 13, 14 of a first cross-sealing- and cutting member 6.2 differ from the location 16 at which the convexities 13, 14 of a second cross-sealing- and cutting member 6.2 are pressed.

[0041] Hence, in case certain locations 16 at the surface of the first cross-sealing- and cutting member 6.1 are worn, the second cross-sealing- and cutting member 6.2 is changed by a cross-sealing- and cutting member 6.2 with different distances D1 , D2 and the production can be continued. Only the second cross-sealing- and cutting member 6.2 has to be exchanged. Figures 5a, b show an embodiment of the inventive toll. Reference can be made to the elaborations according to Figures 2 and 3. However, in the present case, the distance D1 is different form the distance D2 of the respective convexity to a plane / axis 12. In the present case, the distance D1 is larger than the distance D2.

[0042] Figure 5a shows a production configuration for a number of cycles. After the locations 16, again which the convexities 13, 14 are pressed are worn, one of the cross-sealing- and cutting member 6.1 , 6.2, here 6.2, is turned by 180° around the depicted axis 12. The resulting configuration is shown in Figure 5b. The convexities 13, 14 are pressed against different locations at the surface of the first cross-sealing- and cutting member 6.1 and the production can be commenced without exchanging a member.

[0043] Figure 6 shows yet another embodiment of the present invention. In the present, the position of the first- and second cross-sealing- and cutting member 6.1 , 6.2 is changed after a number of production cycles as indicated by the double arrow. This changes the location at which the convexities are pressed against the surface of the first cross-sealing- and cutting member 6.1 so that the production can be continued even though the locations first used are worn. This increases the tool life of the first cross-sealing- and cutting member 6.1 and hence saves cost.

[0044] List of Reference Signs:

[0045] 1 vertical flow-wrapper

[0046] 2 form-fill tube

[0047] 3 form shoulder

[0048] 4 film tube

[0049] 5 longitudinal-sealing means

[0050] 6 cross-sealing and cutting means,

[0051] 6.1 first cross-sealing- and cutting member, sonotrode

[0052] 6.2 second cross-sealing and cutting member, anvil

[0053] 7 package, package, pouch

[0054] 8 frame / housing of the vertical flow-wrapper

[0055] 9 reel

[0056] 10 transport direction

[0057] 11 cutter

[0058] 12 axis / plane of the cross-sealing and cutting means, cutting plane

[0059] 13 first convexity to apply the bottom seal

[0060] 14 second convexity to apply a top seal

[0061] 15 indentation

[0062] 16 location against which the convexities are pressed

[0063] 17 transportation direction of the film

[0064] D1 first distance between middle axis and first convexity

[0065] D2 second distance between middle axis and second convexity

Claims

Claims:1 . Cross-sealing and cutting means (6) for a flow-wrapper (1 ) comprising first- and second cross-sealing- and cutting members (6.1 , 6.2) which cooperate during sealing to apply a pressure to a film to be sealed and during cutting of the sealed film tube, wherein the first cross-sealing- and cutting member (6.1) comprises an indentation (15) provided in a plane (12) and the second cross-sealing- and cutting member (6.2) comprises: a cutter (11 ), which, during cutting enters the indentation (15) and- two convexities (13, 14), one convexity (13) having a first distance (D1) from the plane (12) and the other convexity (14) having a second distance (D2) from the plane (12), characterized in, that the distances (D1 , D2) are not equal.

2. Set of a cross-sealing and cutting members (6.1 , 6.2 ) for a flow-wrapper (1) comprising a first- and two second cross-sealing- and cutting-members (6.1 , 6.2) which cooperate during sealing to apply a pressure to a film to be sealed and during cutting of the sealed film, wherein the first cross-sealing- and cutting member (6.1) comprises an indentation (15) provided in a plane (12) and the second cross-sealing- and cutting member (6.2) comprises: a cutter (11 ), which, during cutting enters the indentation (15) and two convexities (13, 14), one convexity (13) having a first distance (D1) from the plane (12) and the other convexity (14) having a second distance (D2) from the plane (12), characterized in, that the first and second distance (D1 , D2) of the indentations of one second cross-sealing- and cutting member (6.1 , 6.2) is different from the first and second distance (D1 , D2) of the indentations of the other second cross-sealing- and cutting member (6.1 , 6.2).

3. Vertical flow-wrapper (1) having the cross-sealing and cutting means (6) according to claim 1 and / or one first- and one of the two second cross-sealing- and cuttingmembers (6.1 , 6.2) of the set according to claim 2.

4. Method to improve the tool-life of a first cross-sealing- and cutting member (6.1), characterized in, that the location (16) at the first cross-sealing- and cutting member (6.1) against which the convexities (13, 14) of the second cross-sealing- and cutting member (6.2) is pressed is changed after a certain number of production cycles.

5. Method according to claim 4, characterized in, that the second cross-sealing- and cutting member (6.1 ) is turned by 180° after a number of production cycles.

6. Method according to claim 5, characterized in, that one cross-sealing- and cutting member (6.1 , 6.2) is turned around an axis (12) perpendicular to a transportation direction (10) of the film (7).

7. Method according to claim 4, characterized in, that that a second cross-sealing- and cutting member (6.2) is replaced by a different second a first cross-sealing- and cutting member (6.2).

8. Method according to claim 7, characterized in, that the replacement member has a different distance (D1 , D2) than the member to be replaced.

9. Method according to claim 4, characterized in, that the vertical position of the firstand second cross-sealing- and cutting member (6.1 , 6.2) is change relative to each other.

10. Method according to one of claims 4 - 8, characterized in, that it comprises a control system which provides a signal when the locations (16) have to be changed.

Images